Needle-thread-controlling mechanism for sewing machines



Se t. '3, 1929. J. BERGER 1,726,880

EEDLE THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed March 4, 1927 5 Sheets-Sheet l Alli i I N3 I a 23 \WE I 1 9.

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Sept. 3, 1929. J. BERGER 1,726,880

NEEDLE THREAD CONTROLLING MECHANISM FOR SEWING MACHINES 5 Sheets-Sheet 2 Filed March 4, 1927 'Sept. 3, 1929. J. BERGER 1,726,880

NEEDLE THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed March 4, 1927 5 Sheets-Sheet 3 $11 WWW J. BERGER Sept. 3, 1929.

NEEDLE THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed March 4, 1927- 5 Sheets-Sheet 4 I I i Sept. 3, 1929. J, BERGER 1,726,880

NEEDLE THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed March 4, 1927 5 Shets-Sheet 5 showing a portion of the end of the work- Patentecl Sept. 3, 1929.

JOSEPH BERGER, OF UTICA, NEW YORK,

ASSIGNOR TO UNION SPECIAL MACHINE COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

NEEDLE-THREAD-CONTROLLING MECHANISM FOR SEWING IMIACHIN13S.

Application filed March 4, 1927.

The invention relates to new and useful improvements in sewing machines, and more particularly to the needle thread controlling mechanism.

An object of the invention is to provide a thread controlling mechanism for the needle or needles which includes devices connected to the presser foot, so that as the presser foot is raised and lowered by the varying of the thickness of the material being stitched, the amount of thread supplied to the needle or needles will be varied, which devices are so constructed that the raising of the presser foot from the material, for removing or inserting the material in the machine, will not draw any thread from the supply.

Another object of the invention is to provide a thread controlling mechanism for sewing machines which includes stationary and movable thread guides, one of which movable thread guides is connected to the presser bar so as to be moved thereby with the up and down movements of the foot during the feed cycle, said guides being so positioned that when the foot is lowered-by the lowering of the feed dog at the end of the feed stroke, the needle thread or threads will be drawn upon by the movable guide connected to the support;

Fig. 3 is a sectional view through the housing for the needle bar at right angles to the main shaft;

in end elevation of the needle bar housing;

Serial No. 172,775.

Fig. 6 is aview showing diagrammaticallv the needle thread controlling mechanism with the needle at the upper end of its stroke;

Fig. 7 is a similar view, but showing the needle all the way down;

Fig. 8 is a detail view showing the presser bar lowered and the position of the stud which shifts the movable thread guide;

Fig. 9 is a similar View showing the position of the controlling stud for the presser fqoot as lifted through the action of the feed Fig. 10 is a similar view. showing the position of the controlling stud when the presser foot is raised from the material.

The invention is directed broadly to a needle thread controlling mechanism for sewing machines, and more particularly to the needle thread controlling mechanism in a machine which is adapted to stitch knit goods. The machine may be provided with one needle, or a plurality of needles, and cooperating with said needle or needles is a thread carrying looper. The needle or needles are carried by a needle bar which is reciprocated by aneedle lever, and this needle lever carries a movable thread guide. There is also a movable thread guide on the upper end of the needle bar. There is a stationary thread guide on the housing through which the thread passes from the thread guide on the needle actuating lever to the thread guide on the upper end of the needle bar. The thread guide on the needle actuating lever moves above and below this stationary thread guide. It moves below the stationary thread guide when the needles are moved down into the fabric. It moves a 'suflicient distance below said stationary guide to take up the slack in the needle thread, so that when the needle is at the lower end of its stroke, the needle thread is substantially taut. This insures that the proper needle thread loop is thrown out by the needle for the looper to enter. There is also a movable thread guide which is connected up to the presser foot, so that said guide is moved downwardly when the presser foot is raised, and is raised when the presser foot is lowered. The means which shifts the last-named movable thread guide includes a stud carried by and movable with the presser bar, and a cam plate which is connected to the movable guide for shifting the same. Said cam plate is provided with a cam slot in which the stud moves. This slot is shaped so that when the stud is raised and lowered by the raising and lowering of the presser foot. due to the variation in the thickness of the fabric, the guide is shifted so as to cause more or less thread to be pulled from the supply. The slot is also shaped so that when the presser foot is moved out of engagement with the fabric, or back into engagement with the fabric, then there is no movement imparted to the thread guide. Associated with this last'named movable thread guide is a stationary thread guide on the housing. The movable thread guide engages the thread between this stationary thread guide and the movable thread guide on the needle actuating lever. Whenthe thickness in the fabric increases, this movable thread' guide connected to the presser bar will be lowered so that more thread is given up to the needles. When it is lowered by the increase in thickness of the fabric, then the movable thread guide on the needle actuating lever will move to a greater distance above this movable guide connected to the presser bar, and this will draw more thread from the supply. The presser bar is lowered with the lowering of the feed dog, and this occurs on the first part of the downward movement of the needle. It is at this time that the looper is beginning its retracting movement, and the needle thread loops are still about the looper. The downward movement of the presser bar through this downward movement of the feed dog will cause the movable thread guide connected to the presser bar to be raised slightly, and this will draw on the needle thread so as to insure that the needle thread loop of the previous stitch which is around the looper will be drawn taut, and thus properly held positioned on the looper, so that the needle will enter its thread triangle.

Referring more in detail to the drawings, my improved thread controlling mechanism is shown as applied to a sewing machine consisting of a supporting standard 1 which is provided with a forwardly projecting bracket 2 at its upper end, carrying a frame 3 in which the main shaft 4 is journaled. The main shaft 4 is driven by a belt wheel 5, and said shaft is provided with a hand wheel 6. The frame 3 is provided with a depending vertical member, at the lower end of which is attached the work supporting arm 7. This Work supporting arm is suspended and is cylindrical in shape. Located within said work supporting arm is a feeding mechanism, which as shown, is provided with a main feed dog 8 and an auxiliary feed dog 9. The two feed dogs are given a differential movement in the usual manner, and thus it is that the machine is particularly adapted for operating upon knit material.

The work is held on the work support by a presser foot 10, and the feeding mechanism is so timed and operated as to feed the material ofi from the end of the work supporting arm. This presser foot 10 is carried by a presser bar 11.

The frame 3 also supports a housing 12 which projects forwardly from the frame 3 and is located in a plane passing through the main shaft 4 of the machine, substantially at right angles. This presser bar 11 ismounted in the head at the free end of this housing 12. A spring 13 encircling the upper end of the presser bar, bears against a lug 14 at its lower end, and bears against an adjustable sleeve 15 at its upper end. The sleeve 15 encircles the presser bar 11, and this spring urges the presser bar agaisnt the feeding mechanism. When the feed dogs pass up through the throat plate and engage the material, they lift the material from the throat plate, lifting the yielding presser foot therewith; then the feed dogs move forward to feed the material, after which the feed dogs are lowered, and as the feed dogs lower, the presser foot will move down with the feed dogs and clamp the material against the throat plate. This is the usual action in a four motion feed dog construction.

The presser bar is provided with a lug 16 carrying a pin 17. A rock lever 18 is provided with an arm 19 which extends under neath this pin 17 This rock lever is pivoted at 20 to the housing 12. The rock lever is actuated by a link 21 which is connected to a rock shaft 22 mounted on the standard 1. This rock shaft 22 carries an arm 23 which may be connected through a suitable flexible connection with a treadle or knee shift; A spring 24 (see Fig. 4) is connected to this link 21, and to a pin 25 carried by the housing. This spring tends to move the link 21 and rock lever 18, so as to permit the presser bar to move down on to the material through the action of the spring 13.

In the present machine, I have shown three needles 26, 27 and 28. These needles are carried by a needle bar 29 which is mounted in the head at the free end of the housing 12. Cooperating with these three needles within the work supporting arm is theusual thread carrying looper. The needles are set abreast with the points thereof at different heights, and the looper enters first the needle thread loop of the needle at the right,'as viewed in Fig. 2, then the central needle, and then the needle at the left. This part of the stitch forming mechanism is' of the usual construction and further description thereof is not thought necessary.

The .needle bar is provided with a collar 30. The needle actuating lever 31 is mounted on a bearing shaft 32. This shaft is journaled in suitable hearings in the housing 12. A link 33 is pivoted at 34 to the needle actuating'lever 31, and is also pivoted at 35 to the collar 30 fixed to the needle bar. The main shaft 4 is provided with a crank 36 and a link 37 cooperating with said crank is attached to a stud fixed at 38 to the end of the needle actuating lever 31. As the main shaft r0- tates, the needle bar will be reciprocated in the housing 12.

Mounted on the upper end of the needle bar is a projecting arm 39 which is provided with three thread guides for the threads for the needles. Mounted on the housing 12 is a loop or thread guide 40. Mounted on the needle actuating lever adjacent the connection of the link 33 to the lever is an arm 41 which is provided with a series of thread guides 41*, at least one for each needle thread.

An arm 42 is fixed to a shaft 43 journaled in the housing 12, and this shaftis provided with a plate 44. The plate 44 is carried by a collar 45 which is fixed to the shaft 43 by a set screw 46. This arm 42 is provided with a series of thread guides 47. Adjacent the thread guides 47 is a bracket 48 which is provided with a series of thread guides 49. A rod 50 is attached to the housing, and projects over the frame 3, and is parallel thereto. This serves as a guiding passage for the threads. The bracket 2 is provided with a support 51 on which is mounted a series of tensions. The three tensions 52 are for the needle threads. The tension 53 is for the covering thread, and the tension 54 is for the looper thread. The threads from the tensions 52 pass beneath the rod 50, thence through the thread guides 49 to the thread guides 47, and from thethread guides 47 to the thread guides 41*, thence through the thread guiding loop 40 to the thread guides 39 at the upper end of the needle bar. From this point, the threads are led to the needles.

The thread guides 41, as the needle bar reciprocates, move from a position above the thread guide loop 40, as shown in Fig. 6, to a position well below the same, as shown in Fig. 7. On the downward movement of the needle actuating lever, the needles are moved into the material, and to the lower'end of their stroke. This movement of the thread guides 41 beneath the thread loop 40 will take the slack out of the needle threads, so that when the needles reach the lower ends of their stroke, the needle threads are substantially taut. This insures a proper loop formation in the needle threads for the looper to enter on the up-stroke of theto set the stitch,.and pull off the proper amount'of thread for the next stitch formation. r

The cam plate 44 is provided with a slot 53. A stud 54 carried by a collar 55 is located in said cam slot. This collar 55 is adjustably mounted on the upper end of a rod 56, and the rod 56 is fixed to an arm 57 carriedby the sleeve 14 on the presser bar. As the presser bar is raised and lowered, this rod 56 will be raised and lowered, and this will shift the position of the stud 54 in the cam slot 53. This cam slot is provided with a portion 54*, the walls of which are set. at an angle to the path of movement of the stud 54. The stud 54 moves in a vertical direction with the lifting of the presser bar, and when this stud engages the wall 54-, it will shift the cam plate 44, thus rocking'the shaft which carries'the arm 42. This movement of the arm 42 will shift the position of the thread guides 47. The upper portion of the cam slot 53' has a substantially vertical wall 54 and therefore, when the stud -54 reaches the upper portion of this cam slot, it-will impart no movement to the cam plate and no movement to the thread guides 47 When the thickness in the fabric increases, it will raise the presser foot, and this raising of the presser foot, will shift the cam plate44, so as to lower the arm 42 and the thread guides 47 This lowering of the thread guides 47 will cause the thread guides 41 to draw a little more thread from the supply. On the other hand, when the thickness of the material decreases, then the thread guides 47 will be raised, and less thread will be drawn from the supply. Thus it is that a proper amount of thread is supplied to take care of the variation in the thickness of the materials passing beneath the presser foot. When it is desired, however, to raise the presser foot from the material, the stud 54 will pass into the upper portion of the slot and along the wall 54 and the cam plate 44 will not be moved, and therefore, the thread guides 47 will not be shifted during this raising of the presser foot from engagement with the material, and the lowering of the presser foot into engagement with the material. It will be understood, of course, that if there is a thin piece of material in the machine, the lifting of the presser foot to the extent that it would be lifted by the increase in the thickness of the material will shift the thread guides, and where I refer to the raising of the presser foot from the material, I have reference to the raising of the presser foot from the position of maximum lift by the increased thickness of fabric. By this arrangement, the drawing of undesirable thread from the supply, due to the lifting of the presser foot to take out or replace the material, is avoided.

Duringthe feed cycle, the feed dog raises the presser foot, not from the material, but from the throat plate, the material being raised with the feed dog. At the end of the feed cycle, the feed dog is lowered and the material again placedon the throat plate.

This lowering movement of the feed dog causes a lowering movement of the presser foot, and the lowering movement of the presser foot through the cam plate 44, will cause a slight swinging of the arm 42, and a movement of the thread guides 47 so as to draw on the thread. At this time, when the presser foot is descending, due to the clownward movement of the feed dog, theneedle thread loops are about the looper, and the looper is beginning its retracting movement. This drawing on the needle thread will insure that all slack is taken from these needle thread loops around the looper, and that they are thereby properly positioned on the looper so that the needles will enter their proper thread triangles.

From the above it will be apparent that I have-provided thread controlling mechanism for the needle threads, wherein the thread is controlled so as to avoid any objectionable slack at any time during the stitch-formation, wherein the thread is drawnfrom the supply in accordance with the variation in the thickness of. the material, and wherein no thread is drawn from the supply through the act of lifting the presser foot to remove or replace the material being stitched.

The looper thread after leaving the tension 54, passes through a suitable guide and is led to a thread gripping device 58, and thence,

to a rotary take-up 59, and from this take-up it is led through suitable guiding channels to the looper. Thethread gripping devices and the take-up are mounted on the main shaft 4 on the frame 3. The coverin thread after leaving the tension 53 passes eneath the bar 50, and thence through one of the thread guides 47; thence through one of the thread guides 41 and thence through a tension 60.

Associated with the needles is an oscillating thread guide 61 for this covering thread, and cooperating with this oscillating thread guide is a movable thread hook62. This thread guide and thread hook form a loop in the covering thread, which one of the needles enters. The material being stitched may have itsedges upturned and trimmed by the trimming blade 63 cooperating with a stationary trimming blade on the presser foot. After the edges are trimmed they are turned into. overlapped relation and passed to the stitching mechanism. This covering thread laying mechanism and the trimming mechanism, form no part of the present invention, and will not be described in detail. 7

It is obvious that minor changes in the details of construction and the arrangement of the parts may-be made without-departing from the spirit of the invention as set forth in the appended claims.

Having thus described the invention, what I claim as new and'desire to secure by Letters-Patent, is- 1. The combination of a needle, a needle, bar, a needle bar actuating lever, a guide for the needle thread on the upper end of the me dle bar. a guide for the needle thread on said lever, a stationary thread guide engaging the needle thread between said first-namedguides and positioned whereby said guide on I the needle lever draws on the needle thread as the needle approaches the lower end of its stroke, and the guide on the needle bar draws off said thread as the needle approaches the upper end of its stroke, a shiftablegui'de engaging the needle thread between the guide on the needle lever'and the supply, a presser foot and device connecting said shiftable guide with the presser foot whereby said guide is shifted as the thickness of the material varies and the supply of thread varied to accord therewith.

2. The combination with a stitch forming mechanism having a needle and means for reciprocating the same; of a needle thread controllying'mechanism including a thread guide movable by said means for reciprocating the needle for drawing thread from the supply,a cooperating thread guide located between said movable guide and the supply, and devices connecting the presser foot with said last-named guide for shifting the guide when the thickness of the material varies whereby the amount of thread drawn off is in proportion to the thickness'of the material being stitched, said devices connecting the guide and presser foot being constructed so that the movements of the presser foot out of and into engagement with the fabric are ineffective to shift said guide.

3. The combination with a stitch forming mechanism having a needleand'mea'ns for reciprocating the same of a needle thread controlling mechanism including a thread guide movable by said means for reciprocating the needle for drawing thread from the supply, a cooperating thread guide located between said movable guide and the supply, a plate connected to said last-named thread guide for shifting the same, a stud carried by the presser bar and movable with the same, said plate having a slot in which said stud moves, said slot being shaped so that the raising and lowering of the presser foot by variation in the thickness of the material beneath the same varies the amount of thread drawn off in proportion to the thickness of the material being stitched, and said slot being shaped so that movements of the presser foot out of and into engagement withthe fabric are ineffective to shift said-guide. r

= 4. The combination with a stitch forming mechanism having a needle and means for reciprocating the same;lof a needlethread controlling mechanism including a thread guide movable by said means for reciprocating the needle for drawing thread from the supply, a cooperating thread guide located between said movable guide and the supply, a plate connected to said last-named thread guide for shifting the same, a stud carried by the presser bar and movable with the same, said plate having a slot in which said stud moves, said slot being shaped so that the raising and lowering of the presser foot by variation in the thickness of the material beneath the same varies the amount of thread drawn off in proportion to the thickness of the material being stitched, and said slot 15 lengthwise of the pressure bar for varying 20 the eflective control of the shiftable thread guide.

In testimony whereof, I aflix my signature.

JOSEPH BERGER. 

